One vertex per element, one color per generator, with an edge from x to x·s.
(9,10)(11,13)(12,15)(14,22)(16,18)(17,24)(19,20)(21,23)(25,26,31,34)(27,33,29,32)(28,37,39,30)(35,36,38,40)(1,2,5,6)(3,7,8,4)(9,11,16,15)(10,13,18,12)(14,19,24,23)(17,21,22,20)(25,27,31,29)(26,32,34,33)(28,35,39,38)(30,36,37,40)(2,6)(4,7)(9,12,16,13)(10,11,18,15)(14,20,24,21)(17,19,22,23)(25,28,31,39)(26,30,34,37)(27,35,29,38)(32,36,33,40)(1,3)(2,4)(5,8)(6,7)(9,13,16,12)(10,11,18,15)(14,21,24,20)(17,19,22,23)(25,27,31,29)(26,32,34,33)(28,35,39,38)(30,36,37,40)(9,14,16,24)(10,17,18,22)(11,19,15,23)(12,20,13,21)(25,29,31,27)(26,33,34,32)(28,38,39,35)(30,40,37,36)(1,4)(2,3)(5,7)(6,8)(9,15,16,11)(10,12,18,13)(14,23,24,19)(17,20,22,21)(25,30)(26,28)(27,36)(29,40)(31,37)(32,35)(33,38)(34,39)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.